Pier and Post in Cold Climate ...Hydro-Bore??

[BaldEagleVT]

So in Central VT we need 36" or more pier depth to get below frost line. We have pier frost jacking reports..  So I'm contemplating deep piers in a rocky hillside.. Then I wondered..  Can one Excavate with water instead of a shovel?  If theres room for the post and rebar, do I care if there's some builders mixed in?  Does 'side boulder' elevate frost jacking probability?
Thanks for your thoughts!

[Don_P]

If I'm reading right, will a rough edged pier frost heave? Oh yeah. Will there be any soil structure left to stabilize the posts laterally, I doubt it. Is there a reason not to call in a backhoe and put in a continuous footing and perimeter wall foundation as per minimum?

[BaldEagleVT]

Oh, I forgot to mention the pouring in of cement..  But still rough edged, which is the opposite of smooth and covered with plastic..

It's on a rocky hillside above a fire pond.  Not sure how much site work required to clear for continuous footing.  I guess if I can get a small backhoe up there, I could have that dig the pier footings..?

[Don_P]

If you have a backhoe there I'd put in a proper foundation and be done with it. Piers are an engineer required foundation for good reason, they are typically done poorly and are one of the hardest things to fix once a house is on top of them.